Quantifying changes in the spatial pattern and extent of flooded-inundated areas using imagery and landscape metrics

Abstract

[Abstract]: A case study of the Lower Balonne floodplain in Queensland, Australia, was conducted to quantify the changes on the spatial extent and patterns of flooded and inundated areas in a large, ephemeral floodplain. The study employed digital image processing techniques to produce inundation maps from the 1994 and 2004 flood events captured by Landsat 5 imagery. Using a geographic information system (GIS) based landscape patterns analysis program (Patch Analyst), selected landscape metrics pertaining to patch size, shape, and connectivity were calculated and analysed. The results show not only the significant reduction (44,658 ha corresponding to 43% decrease) in the extent of the flooded and inundated areas, but also the changes on the configuration of these patches. They became more fragmented and isolated, particularly in the lower region of the floodplain. The use of region-based analysis, rather than focusing solely on total area, has provided more information that subsequently linked these changes with water storage developments. This study concluded that the use of landscape metrics, along with conventional mapping of inundation extent, can support the monitoring of floodplain areas.